1. Field of the Invention
The present invention relates to a dental fine filling method for protecting or restoring pits and fissures or minute decalcified surface lesions in enamel by rubbing therein a powder, granules, a solution (suspension) or paste containing hydroxy-apatite or tetracalcium phosphate with or without adjuvants and then optionally covering the site with a polymer or fluoride, and to a dental fine filler used for such filling, which is based on hydroxy-apatite or tetracalcium phosphate which may or may not contain calcination-promoting protein or a coating agent.
2. Description of the Prior Art
When plaque deposits on the surface of enamel, acids produced therein by microorganisms gradually etch the enamel and produce minute lesions therein. (This process is hereinafter referred to as decalcification. It is recognized that decalcified lesions are recalcified and restored by saliva.) One the enamel is decalcified, plaque is soon redeposited on the decalcified lesions, even though it is removed by brushing, so that the enamel is subjected to repeated decalcification due to acids. Thus, decalcification advances through repetitive occurrence of decalcification, removal of the plaque, redeposition of the plaque and decalcification, ending in visually detectable caries. In conventional dental treatment, the hard tissue of a visually detectable carious tooth including its periphery is resected, and various plastics, cements or metals are filled in the resected site as a replacement of the lesion. However, this method requires a high degree of technical skill. In addition, if filling is incomplete, the carious process again advances from the periphery of the filling material. In recent years, a sealant method has been developed in which the pits and fissures that are most susceptible to caries or decalcified lesions caused by the incipient decalcification are occluded with a sealant that is a polyacrylate, polyurethane or other polymer to isolate them from the oral environment, thereby preventing caries from occurring. According to the sealant method, the pits and fissures or decalcified lesions, which may have been treated with acids depending upon the sealant agents used, are occluded therewith to prevent plaque from occurring and acting on the site, thereby preventing caries. In this method, however, insufficient or excessive acid treatment or deposition of saliva on the acidtreated surface may cause a decline in the bonding force of the sealants with respect to pits and fisssures or decalcified lesions. The sealants, if occluded in too large an amount, may also break due to mastication and biting. Thus, with the sealant method, there is the possibility that the sealants may dislodge depending upon their quality and the technical skill of the operator, and the effectiveness of the method varies with the clinical skill of the operator. With the sealant method, difficulty is encountered in covering minute decalcified lesions with the sealant agents and in the recalcification of the covered decalcified lesions since they do not come into contact with saliva. In efforts to enhance resistance to caries by the reinforcement or protection of dentin, fluorine ions are applied to the surface of teeth or added to drinking water and foods. However, a special technique is required for the manipulation of fluorine compounds. As a method of depositing an enamel composition on the surface of teeth, Japanese Patent Application Laid-Open (KOKAI) No. 47-1567 proposes to form brassid on the surface of teeth using as the medium a gelatiniform substance prepared in such a manner that its toxicity and final pH do not harm the mouth, and to convert brassid to hydroxy-apatite. However, this method not only requires an extended period of time for the conversion of brassid to hydroxy-apatite, but also requires use of the gelatiniform substance so as to help bond brassid to the surface of teeth.
Application of fluorine exists as a procedure for reinforcing the surface of teeth, and the sealant method or the method disclosed in Japanese Patent Application Laid-Open (KOKAI) No. 47-1567 is available as a procedure for protecting the pits and fissures and restoring decalcified lesions. However, these methods require special clinical skill and involve the difficulties mentioned above.